The present invention relates to a device for controlling or correcting the readout of the day of the week or of the date for a watch, particularly a wrist watch, comprising at least one bi-directional electric motor, at least one mechanism coupled to this motor to drive a day disk or a date disk and at least one electronic circuit designed to transmit control impulses to this motor.
In known wrist watches, of the analogue type, the change of date and of day of the week habitually occurs at 24 hours. This change occurs within a very short period of time, thanks to the release of energy which has been accumulated by a suitable mechanism over a longer or shorter period of time. If the user changes time zone, in the sense of local time being behind the local time of the site of origin, and if he moves the needles backwards roughly at midnight, the correction of the day and of the date can not be made at the same time as the correction of the hour. In these conditions, the information regarding day and date displayed on the watch are incorrect for at least a part of the time separating the moment when the operation was carried out and midnight at the new geographical site. This constitutes a drawback. The object of the present invention is to find a solution to this drawback whilst avoiding making concessions on other matters, such as, for example, the supression of the instantaneous nature of the change of date and/or of the day of the week.
Once the instantaneity of the change and the symmetry of passing from one day of the week and/or one date to another at midnight have been achieved, the object of the invention is also to guarantee, in an almost absolute way, the reliability of the readout of the day and of the date. This reliability implies safety against shocks, safety against the rated steps of the drive motor(s), of day and/or date disks(s) and an automatic starting-up of the drive mechanism of these disks after the watch has stopped or the battery has been changed. With regard to this last point, on certain watches, if the readout of the day or date appears offset or incomplete in the corresponding window after changing the battery, the displacement has repercussions from day to day because no automatic means for making the necessary correction is provided.
The control or correction device in accordance with the invention is designed to resolve all these problems and to remove all the drawbacks of known systems for displaying the day and/or the date on a wrist watch. It is proposed to allow the day and/or the date to be displayed in a precise way in all conditions of use and irrespective of the time zone, and in particular to enable the change of day and date in the two directions within a very short period of time.